Calculating the DMA offset between a bus address space and CPU's every time we call phys_to_bus() and bus_to_phys() isn't ideal performance wise, as it implies traversing the device tree from the device's node up to the root. Since this information is static and available before the device's initialization, parse it before the probe call an provide the DMA offset in 'struct udevice' for the address translation code to use it.
Signed-off-by: Nicolas Saenz Julienne nsaenzjulienne@suse.de
--- Changes since v1: - Update commit message so as to explain better the reasoning behind this
drivers/core/device.c | 24 ++++++++++++++++++++++++ include/dm/device.h | 1 + 2 files changed, 25 insertions(+)
diff --git a/drivers/core/device.c b/drivers/core/device.c index 4b3dcb3b37..4255bea24d 100644 --- a/drivers/core/device.c +++ b/drivers/core/device.c @@ -421,6 +421,28 @@ fail: return ret; }
+void device_get_dma_constraints(struct udevice *dev) +{ + phys_addr_t cpu; + dma_addr_t bus; + u64 size; + int ret; + + if (!dev_of_valid(dev)) + return; + + ret = dev_get_dma_range(dev, &cpu, &bus, &size); + if (ret) { + /* Don't complain if no 'dma-ranges' were found */ + if (ret != -ENODEV) + dm_warn("%s: failed to get DMA range, %d\n", + dev->name, ret); + return; + } + + dev->dma_offset = cpu - bus; +} + int device_probe(struct udevice *dev) { const struct driver *drv; @@ -482,6 +504,8 @@ int device_probe(struct udevice *dev) goto fail; }
+ device_get_dma_constraints(dev); + ret = uclass_pre_probe_device(dev); if (ret) goto fail; diff --git a/include/dm/device.h b/include/dm/device.h index 5bef484247..59f711e3dd 100644 --- a/include/dm/device.h +++ b/include/dm/device.h @@ -161,6 +161,7 @@ struct udevice { #ifdef CONFIG_DEVRES struct list_head devres_head; #endif + u64 dma_offset; };
/* Maximum sequence number supported */